1. Field of the Invention
The present invention relates to magnetic flux detector system for determining aircraft heading and more specifically for a correction system that compensates for heading errors introduced by aircraft acceleration.
2. Description of the Prior Art
Magnetic flux detector systems for determining aircraft heading, commonly called flux valves, are well known in the art. Currently, flux valves provide accurate heading information only during non-accelerated flight. During accelerated flight the pendulous flux valve element is displaced or "hangs-off" the vertical and senses both the earth's horizontal magnetic field and a portion of the earth's vertical magnetic field. Unwanted sensing of the vertical field introduces errors into aircraft heading measurement. Prior art systems simply disengaged the flux valve heading output during periods of accelerated flight that exceeded a predetermined threshold. During periods when the flux valve is disengaged, heading information is obtained from a free gyroscope. As a result, prior art systems have the disadvantage of operating for long periods using only free gyro heading information when aircraft acceleration is above a given threshold. Below the acceleration threshold, flux valve heading errors are still introduced as the aircraft experiences small accelerations. The present invention compensates for flux valve heading errors during periods of low level acceleration thereby increasing flux valve heading accuracy and decreases dependence on obtaining heading information from a free gyro.